Shoulder pain can be a persistent and debilitating issue, often stemming from a common condition known as Impingement Syndrome. Also referred to as subacromial impingement, painful arc syndrome, supraspinatus syndrome, swimmer's shoulder, or thrower's shoulder, this condition occurs when the tendons of your rotator cuff muscles—and sometimes the bursa, which are fluid-filled sacs that cushion your joints—become painfully pinched or compressed within a narrow space in your shoulder joint.